Oracle 10g Forms Lesson 13

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Define triggers
Identify the different trigger categories
Plan the type and scope of triggers in a form
Describe the properties that affect the behavior of a trigger

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  • Oracle 10g Forms Lesson 13

    1. 1. Introduction to Triggers
    2. 2. Objectives <ul><li>After completing this lesson, you should be able to do the following: </li></ul><ul><ul><li>Define triggers </li></ul></ul><ul><ul><li>Identify the different trigger categories </li></ul></ul><ul><ul><li>Plan the type and scope of triggers in a form </li></ul></ul><ul><ul><li>Describe the properties that affect the behavior of a trigger </li></ul></ul>
    3. 3. Trigger Overview Event Trigger types Queries Validation Navigation Interaction Internal event Errors/Messages Others PL/SQL Fire PL/SQL PL/SQL Which trigger would you use to perform complex calculations after a user enters data into an item?
    4. 4. Grouping Triggers into Categories <ul><li>Triggers may be grouped into functional categories: </li></ul><ul><ul><li>Block processing triggers </li></ul></ul><ul><ul><li>Interface event triggers </li></ul></ul><ul><ul><li>Master-detail triggers </li></ul></ul><ul><ul><li>Message handling triggers </li></ul></ul><ul><ul><li>Navigational triggers </li></ul></ul><ul><ul><li>Query-time triggers </li></ul></ul><ul><ul><li>Transactional triggers </li></ul></ul><ul><ul><li>Validation triggers </li></ul></ul><ul><li>Triggers may be grouped into categories based on name: </li></ul><ul><ul><li>When-Event triggers </li></ul></ul><ul><ul><li>On-Event triggers </li></ul></ul><ul><ul><li>Pre-Event triggers </li></ul></ul><ul><ul><li>Post-Event triggers </li></ul></ul><ul><ul><li>Key triggers </li></ul></ul>
    5. 6. Defining Trigger Components What event? What action? What level? Type Code Scope
    6. 7. Trigger Type <ul><ul><li>Pre- </li></ul></ul><ul><ul><li>Post- </li></ul></ul><ul><ul><li>When- </li></ul></ul><ul><ul><li>On- </li></ul></ul><ul><ul><li>Key- </li></ul></ul><ul><ul><li>User-named </li></ul></ul>What event? Type Code Scope
    7. 8. Trigger Type Forms Builder Trigger Types
    8. 9. Trigger Code <ul><ul><li>Statements </li></ul></ul><ul><ul><li>PL/SQL </li></ul></ul><ul><ul><li>User subprograms </li></ul></ul><ul><ul><li>Built-in subprograms </li></ul></ul>Type Code Scope What action?
    9. 10. Trigger Scope <ul><li>Levels </li></ul><ul><ul><li>Form </li></ul></ul><ul><ul><li>Block </li></ul></ul><ul><ul><li>Item </li></ul></ul>Code Scope Type What level?
    10. 11. Trigger Scope Event Event Event Order Date
    11. 12. Specifying Execution Hierarchy Form level Block level Item level On-Message On-Message On-Message On-Error On-Error EH = After EH = After EH = Before EH = Override 1 2 3 4 Event Event
    12. 14. Summary <ul><li>In this lesson, you should have learned that: </li></ul><ul><ul><li>Triggers are event-activated program units </li></ul></ul><ul><ul><li>You can categorize triggers based on function or name to help you understand how they work </li></ul></ul><ul><ul><li>Trigger components are: </li></ul></ul><ul><ul><ul><li>Type: Defines the event that fires the trigger </li></ul></ul></ul><ul><ul><ul><li>Code: The actions a trigger performs </li></ul></ul></ul><ul><ul><ul><li>Scope: Specifies the level (form, block, or item) at which the trigger is defined </li></ul></ul></ul><ul><ul><li>The Execution Hierarchy trigger property alters the firing sequence of a trigger </li></ul></ul>

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